Can I install to other than my C: drive which is nearly full?

Installing to C: fails for lack of space. Subsequent attempts fail the same way.

You can make a Custom install, then you will able to choose a place for the software directory. But the Settings (in the LO User profile) will be placed into the Windows User directory by default.

Note: When the C: is nearly full, the Windows and the other softwares will be slow and/or unstable.

You could also run the Libreoffice portable app off a pen drive, or copy the portable LO from the pen drive to another hard drive which should be faster.